Double-pressure set-screw.



A. MENDELSON. DOUBLE PRESSURE SET SCREW. APPLICATION FILED SEPT- 25, l9l4- 1,169,93. v Patented Nov. 16, 1915.

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GE NEW! YORK, N. Y.

DOUBLEJPRESSURE SET-SCREW.

ispecification of Letters Patent.

Patented Nov. 18, 1915.,

Application filed September 25, 1914. Serial No. 863373.

proved Double-Pressure Set-Screw, of which the following is a full, clear, and exact de-' scription.

This invention relates to improvements in set screws and the object thereof is the provision of a screw embodying a shank and a point so connected. as to cause double application of pressure against'an object to be held by turning the shank after the is so engaged with an object as to preent its rotation,v thereby reducing the amount of pressure required to tighten the set screw.

A further object of the invention is to provide a set screw comprising a shank threaded to engage an aperture of a carrying part receiving a member to be held and in which a point is threaded to the shank in an opposite direction to 'the threading of the shank, whereby rotation of the shank after the point has come in binding engagement with an object, will cause the point to move away from the shank as the shank is screwed home, without causing a binding engage mentof the parts with each other, and so that the shank may be made of ordinary machined steel and the engagement member of hardened or tempered steel to cheapen the cost of the set screws but more desirably to obviate the necessity of renewing the entire set screw in the event that the point becomes mutilated or dulled.

Set screws have heretofore been provided in which the shankor threaded part of soft material such as iron or steel was provided with a socket or reduced end, in or to which a point of hardened material was fitted, but when the screw was tightened the point or engaging member would bindingly engage with the shank of the set screw with the result that-the hardened point or engaging member would resist greater pressure than the shank and thus result in the mutilation of the shank and invariably at points at or below the upper end of the engaging memher or point. The disadvantage of a point of this character is that in order to remove the broken part of the screw it will be necessary to drill into the point which isma'de harder than the material employed for the ordinary drill and thus it will be almost im possible to replace a set screw. Furthermore, forv each degree of pressure exerted against the shaft or element which is held or engaged by the point a corresponding pressure must be exerted in turning the screw, and since it is necessary for the point to turn relatively to" the shank this pressure is materially increased by the friction between these parts in order to tighten the set screw, whereas in the present invention the point being held against movement without interfering with the turning of the shank, the engaging ineinber or point may be made cross-sl'laped, star-shaped, chisel-shaped or any other particular form which will bite into the shaft, oi-other object or part tobe held against movement with respect to a fixedor carrying part, whereby a more positive engagement is effected.

With the above and other objects in view, the invention resides in the peculiar combination and arrangement of parts 'to be here inafter more fully described, illustrated and claimed, it being also an object to provide a device which is simple in construction, durable and eflicient in operation.

Reference'is to be had to the accompanying drawings forming a part of this specification, in which similar characters of reference indicate corresponding parts in all the views, and in which Figure 1 is a side elevation ofthe preferred form of double pressure set screw constructed in accordance with the invention; Fig.' 2 is a sectional view thereof showing the same applied to an object to be held but before being screwed home; Fig. 3 is a similar view showing the device after it has been screwed home or tightened; Fig. 4 is a face view ofthe engaging end of the point of the set screw Fig. 5 is a sectional view of a modification of the invention; and Fig. 6 is a face view of a modified form of point or engaging member.

As illustrated in Figs. 1 to 4, inclusive, the preferred embodiment of the invention comrises a set screw in which double pressure is exerted against the shaft or element to be held when thescrew is turned, and for this purpose the screw comprises a shank part '10 having a tool engaging end or .screw headyl-l of the-same size or enlarged rela 'tively thereto for the application of a screw driver or wrench in turning the same. The shank'is provided with a reduced exteriorly threaded portion'or extension 12, the extent of direction of the threads of the reduced portion or extension being opposite to that of the threads of the shank proper and adapted to receive an engaging member or point .13 thereon. This point is interiorly threaded for engagement with the reduced portion or extension 12 but is smooth exte riorly and may be made to fit relatively snugly in the carrying part 14 to which the set screw is applied. This engaging member or 'point is, however, preferably madeslightly smaller than the external diameter of the shank so that it may be readily removed.

In the use of the set screw for engaging an element. or part 15' to be held, the engaging member or -point is threaded onthe ex,- tension 12 to'contact with a shoulder 16 produced by the reduced'extension 12 with the body of the shank or set screw proper so that when the set screw isscrewed home and, the engaging member or point is in binding contact with the part 15and, the screw is tightened, the point will be, held against turning and rotation of the shank will result in the point moving away from-theshank due to its threaded engagementtherewith,

Whether the shank is made of reduced sizeor not, so that the screw may be tightened with a minimum application of pressure and whereby the provision of two sets of,

21. The point is smooth on its lateral sur-.

face and is threaded to the shank in a direction opposite to the direction in which the shank engages the carrying part so that the action is the same as just describedwhen tightening the'set screw. The engaging face of the point -21 may be made cross-shaped, chisel-shaped or any other particular form,

. as shown at 22, to positively bite into the object engaged thereby. This form of the invention, however, does not possess the salient advantage existent in the preferred form of the invention, in that, should the shank break in use it would be more likely to break adjacent to the reduced=portion20 sothat it would be necessary to drill .into this part to remoyethe surrounding threaded portion of;

Having thus described my invention, what ters Patentis 1.'A double pressure set screw compris- I claimas new and desire to secure by Leting an exteriorly threadedshank and an 'engaging-member or point oppositely threaded to the shank and adapted when held against turning by engagement with an object to be held during the tightening of the set screw by turning the shank, to move away from the shank and in binding contact with the object engaged thereby, the strain being distributed upon the two sets of threads.-

-2. A double pressure set screw comprising a threaded shank having an engaging end and a point threaded to the shank to unscrew therefrom when the shank is turned and the point is held against rotation, said point being adapted to loosely fit the seat of a carrying part for the set screw and the shank being of softer material than the point.

3. A set screw comprising an external shank having a reduced externally threaded extension, means whereby the shank may be turned and an engaging member having an internally threaded socket engaged on the extension, the direction of extent of the-threads of the shank being opposite to that of the threads onthe extension to cause said parts to move toward and awayfrom each other when the screw is applied and removed respectively, said engaging member having a biting end.

4. A set screw comprising a pair of sec' tions, one of said sections being adapted for movable engagement with a carrying element and the other section being adapted to" clamp an object to be held against movement with respect to said carrying element and coiiperative means movably connecting said sections. to cause opposite movement and separation thereof when the first named section is moved in operative engagement with the carrying element and the other-section is frictionally engaged with anyobject to be held, said means serving to cause said sections to move in reverse directions when the first named section is oppositely operated. v

5. A double pressure set-screw compris' ing a shank externally threaded to screw into an object, and a pointfrela'tively rota table and united by screw threads with the shank, the threads between the point and name to this specification inthe presence of shank being of opposite pitch-#0111 the pitch two subscribing Witnesses. ef the threads 01% the shank, eald polnt hav- AARON MENDELSON 111g 1ts end face shaped to blte mto an 030- 5 ject-,-Whereby the point is held against rote- Witnesses:

tion hile the shank is turned home. I JOHN E. B RCH,

In 'testimqny whereof I have signed my GEORGE H. ENSLEE. 

